Direction finding systems using antennas or arrays of antennas have been used in the past on self-propelled aerospace missiles in order to provide steering information to the missiles. The direction finding systems are a form of active or passive radar in which the antennas are used to transmit and receive or receive only, respectively, pulsed electromagnetic signals from the target. The radar technique used may include amplitude or phase monopulse systems. Missiles have been built which have antenna arrays or miniature scanning antennas mounted in the nose of the missile. Such designs are disadvantageous in that precious space inside the missile is consumed by bulky antennas.
The construction and operation of logarithmically periodic antennas is discussed in a two-part series of articles entitled "Log Periodic Antennas", written by Al Brogdon, and which were published on pages 81-85 of the October, 1967 issue of CQ Magazine and on pages 80-85 of the November, 1967 issue of that magazine, the disclosures of which are incorporated herein by reference.
The theory of frequency-independent log-periodic antennas is discussed on pages 18-48 and 18-49 of a chapter entitled "Antennas and Wave Propagation" by W. F. Croswell in Electronics Engineers' Handbook, Donald G. Fink (ed.), (McGraw Hill: 1975). Prior art tracking radar techniques are shown on pages 25-53 through 25-58 in a chapter entitled "Radar, Navigation, and Underwater Sound Systems" by David K. Barton in that same handbook. The two handbook disclosures are incorporated herein by reference.
A variety of wide bandwidth, logarithmically periodic antennas have been used in the past for radio wave reception by amateur ratio operators and others. Logarithmically periodic dipole antennas have been made which consist of a planar arrangement of parallel stubs arranged in equal-length pairs mounted on opposing sides of a boom with alternating feed connections between the stubs.